Combustion Noise in Modern Aero-Engines

Combustion noise has recently been the subject of attention of both the aeroacoustic and the combustion research communities. Over the last decades, engine manufacturershave made important efforts to significantly reduce fan and jet noise, which increased the relative importance of combustion noise. Two main mechanisms of combustion-noise generation have been identified: direct combustion noise, generated by acoustic waves propagating to the outlet, and indirect combustion noise, caused by the acceleration of entropy waves (or hot spots) and vorticity waves through  turbine blades. The purpose of this paper is to describe some of the predicting tools used in combustion noise, as well as to present an overview on some recent experimental studies.